Centralized electronic systems, such as a communication network system or a parallel computer processing system, employ a variety of electronic devices residing in a housing or other suitable enclosure. One type of electronic device included in such systems is the front end rectifier.
The front end rectifier converts alternating current (AC) power into an intermediate direct current (DC) power. Power is received from an AC distribution system, which may be, for example, a 120 volt AC or 240 volt AC system. Electronic rectifying devices convert the received AC power (AC current and AC voltage) into DC power (DC current and DC voltage). Intermediate DC voltage may be, for example, at 48 volts or 12 volts DC, though any suitable intermediate DC voltage may be used depending upon the system design.
FIG. 1 is a simplified block diagram illustrating a conventional front end rectifier 102. Within the front end rectifier 102 is an alternating current to direct current (AC/DC) rectifier 104 and a direct current to direct current (DC/DC) voltage conversion unit 106.
The AC/DC rectifier 104 receives AC power, via connection 108. Connection 108 is illustrated as a single line for convenience, and may be a plurality of wire connections depending upon the nature of the AC power source. The received AC power is converted to DC and output at a voltage that corresponds to the voltage of the AC power source, referred to as the rectified DC voltage. The rectified DC voltage is provided to the DC/DC voltage conversion unit 106, via connection 110.
The DC/DC voltage conversion unit 106 converts the received rectified DC voltage into an intermediate DC voltage. The intermediate DC voltage is provided to the intermediate DC voltage bus 112, via connection 114.
DC power, at the intermediate DC voltage, is then provided to a plurality of DC/DC converter output modules 116a-i, via connections 118. The DC/DC converter output modules 116a-i convert the received intermediate DC voltage into a load DC voltage required by the loads 120a-i, via connections 122. Accordingly, DC current is determined by the loading requirements of the loads 120a-i, plus resistive losses, in the system.
An exemplary power supply system is illustrated and described in U.S. patent application Ser. No. 09/753,056 to Brooks et al., published as publication 2002/0085399, which is herein incorporated by reference in its entirety. Accordingly, individual components of the front end rectifier 102, the AC/DC rectifier 104, the DC/DC voltage conversion unit 106, the DC/DC converter output modules 116a-i and the loads 120a-i are not described in detail herein. Furthermore, various other configurations of components are known that provide the same or similar functionality.
As a simplified illustrative example, assume that the front end rectifier 102 receives three phase, 120 volt AC power. The AC/DC rectifier 104 converts the received 120 volt AC power into a rectified DC voltage that corresponds to 120 volts. Then, the DC/DC voltage conversion unit 106 converts the rectified DC voltage to an intermediate DC voltage, which may be, for example, 48 volts. The DC/DC converter output modules 116a-i receive the intermediate DC voltage, via the intermediate DC voltage bus 112, and convert the received DC voltage to the voltage used by loads 120a-i. Examples of load voltages may be 12.5 volts DC, 5 volts DC or 3.5 volts DC, as illustrated in Brooks et al.
FIG. 2 is a perspective view of the front end rectifier 102 illustrated in FIG. 1. The front end rectifier 102 is configured as a modular unit for convenience. Such modular front end rectifiers 102 may be easily installed or replaced. An enclosure (not shown) facilitates the installation and/or replacement of a modular front end rectifier 102 by providing slots, guides, receptacles or other suitable structure such that a front end rectifier 102 may be easily inserted into position in the enclosure.
Typically, a front end rectifier 102 has a length dimension based upon, in part, the design of the enclosure. Another factor determining the length of the front end rectifier 102 is the layout of the components in the AC/DC rectifier 104 and the DC/DC voltage conversion unit 106.
A connector 202 is provided on the front end rectifier 102 that facilitates easy coupling of the output of the DC/DC voltage conversion unit 106 to the intermediate DC voltage bus 112. For example, the connector 202 may be a blade configured to couple to a receptacle residing on the intermediate DC voltage bus 112. Alternatively, the connector 202 may be a coupling mechanism configured to couple to a portion of the intermediate DC voltage bus 112 that is configured as a bar or other solid structure.
Conventional electronic systems may employ a single front end rectifier 102. The intermediate DC power is distributed to the DC/DC converter output modules 116a-i over the above-described intermediate DC voltage bus 112. The “capacity” of the single front end rectifier 102 is determined, in part, by the total load drawn by the loads of the various electronic devices residing in the enclosure. “Capacity” is the total amount of power that can be converted and/or transmitted by a device or component. Typically, the capacity of the AC/DC rectifier 104 and the DC/DC voltage conversion unit 106 are approximately equal.
Thus, a single front end rectifier 102 may be relatively large when the electronic system has a large number of electronic devices residing in the enclosure and/or or has electronic devices that draw a large amount of DC current. A large single front end rectifier 102 inherently has several disadvantages. Illustrative disadvantages are described below, although there may be other disadvantages not explicitly described herein.
First, when a single relatively large front end rectifier 102 is used, the initial cost is relatively high. For example, the front end rectifier 102 can be designed with sufficient capacity to accommodate the maximum possible load of all electronic devices that may ultimately be installed in the enclosure. That is, initially, capacity of the front end rectifier 102 may not be fully utilized. (Presumably, a smaller front end rectifier sized with a capacity corresponding to the initial loading is less expensive than a larger front end rectifier 102). Thus, the initial installation of a single relatively large front end rectifier 102 (with sufficient capacity for the planned ultimate loading) may be more expensive because of the initial unused capacity.
As noted above, if the initial load of the electronic devices was less than the planned ultimate load, a smaller (less capacity) front end rectifier can be installed initially. However, as the load increases over time, at some point, the smaller front end rectifier should be replaced with the larger front end rectifier 102. Thus, the later installation of the relatively larger capacity front end rectifier 102 may be more expensive because of the added cost of buying both the larger and the smaller front end rectifiers, plus the added installation cost of the later installed larger front end rectifier 102.
Furthermore, the front end rectifier 102 may be relatively long in its physical length since it includes the AC-DC rectifier 104 in series with the DC/DC voltage conversion unit 106. This relatively long length of a conventional front end rectifier 102 (the length illustrated in FIG. 2) may have an adverse impact, or may have a limiting impact, on the design of the enclosure because the total enclosure length will be, in part, determined by the length of the front end rectifier 102.
A single front end rectifier 102 may be subject to a single contingency loss. That is, when the front end rectifier 102 fails, or a component residing in the single front end rectifier fails, the system may become inoperable because of a loss of power. Thus, some system designs require a redundant power supply, resulting in the use of two (or more) single front end rectifiers 102. Additionally, some designs require the use of two (or more) different AC sources (e.g., from separate AC grids). For instance, in combination with two single front end rectifiers 102 for power supply redundancy, accommodating two separate AC sources requires 2N+2 front end rectifiers 102 or N+1 front end rectifiers 102 for each AC grid. Such system designs can consume valuable space and increase costs, among other problems.